Study on the phase transition behavior of poly(butylene adipate) in its blends with poly(vinyl phenol).

The phase transition behavior of poly(butylene adipate) (PBA) crystals in its blends with poly(vinyl phenol) (PVPh) was investigated by infrared (IR) spectroscopy and X-ray diffraction (XRD). The IR and XRD studies indicate that the hydrogen bonding between the C═O group of PBA and the OH group of PVPh developed in the PBA/PVPh blends with the ratios of 80/20 and 50/50 does not influence the solution crystallization behavior of PBA. The phase transition behavior of PBA in the blends is, however, significantly altered by the blending. In the neat PBA, linear changes of the intensities of IR bands at 1077, 930, and 910 cm(-1) are observed in the temperature range of 25-47.5 °C followed by an abrupt change corresponding to the occurrence of β-to-α phase transition. In the blends, the accelerated intensity changes of the those IR bands occur before the β-to-α phase transition, which is contributed to the melting of imperfect β-PBA crystals at relatively lower temperature. In addition, the significantly depressed β-to-α phase transition temperature is also identified.